The present invention relates to a fluid heating device, which is capable of frozen or cooled heating medical fluids, e.g., blood, liquid medicine, until reaching bodily temperature, and a cartridge, which can be detachably attached to the fluid heating device.
In the case of blood transfusion, blood, which has been cooled at temperature of 4-6xc2x0 C., is usually used. If the cooled blood is transfused to a human body, the human body receives much stress.
On the other hand, if the temperature of the blood is higher than 42xc2x0 C., cellular tissues of the blood are apt to be damaged.
Therefore, conventionally, medical fluids to be transfused to human bodies are heated to proper temperature, e.g., bodily temperature, by fluid heating devices.
Conventionally, blood is not directly passed through a fluid heating device. The fluid heating device has a cartridge, which is detachably attached to the fluid heating device and through which the blood is passed and heated. By employing the detachable cartridge, a body proper of the fluid heating device need not be washed and disinfected in spite of keeping sanitary conditions.
Conventional fluid heating devices are disclosed in Japanese Patent Gazettes No. 46-1945 and No. 9-500481.
The conventional fluid heating device disclosed in the Japanese Patent Gazette No. 46-1945 is shown in FIG. 7. A cartridge 9 is a sealed plastic container. The cartridge 9 is formed by assembling a pair of sub-members 8 and 9, and a zigzag fluid path 7 is formed in the cartridge 9. An outlet 4 and an inlet 5 are communicated to the zigzag fluid path 7.
The conventional fluid heating device disclosed in the Japanese Patent Gazette No. 9-500481 is shown in FIG. 8, which is an exploded perspective view. A cartridge 10 includes: a thin spacer 12, in which a zigzag fluid path 11 is formed; a pair of flexible heat conductive films 13, which are receptively adhered on an upper face and a lower face of the spacer 12 with adhesive means 15; and a frame 14 for holding the members 12 and 13.
The zigzag fluid path 11 is enclosed by the thin spacer 12 and the films 13, so the zigzag fluid path 11 is formed in the sheet-shaped cartridge.
When the cartridge 10 is attached to the fluid heating device, heaters (not shown), which are shaped to correspond to the zigzag shape of the path 11, respectively contact an upper face and a lower face of the cartridge 10 corresponding to the zigzag fluid path 11. With this structure, a medical fluid passing through the zigzag fluid path 11 can be heated.
If a sectional shape of the zigzag fluid path is a circular shape, friction between a medical fluid and an inner face of the zigzag fluid path can be small, so that the medical fluid can be flowed efficiently.
But heating efficiency is more important than the flowing efficiency. Thus, contact area between the heaters and the zigzag fluid path must be broader. The zigzag fluid path having the circular sectional shape is not advantageous to improve the heating efficiency.
Therefore, in the Japanese Patent Gazette No. 9-500481, the upper face and the lower face of the cartridge 10, which contact the heaters, are made flat so as to make the contact area broader. Namely, the sectional shape of the zigzag fluid path 11 is formed into a thin rectangle shape.
However, the conventional fluid heating devices have following disadvantages.
In the fluid heating device shown in FIG. 7, the sectional shape of the zigzag fluid path is the circular shape, so the heating efficiency is low.
In the fluid heating device shown in FIG. 8, the sectional shape of the zigzag fluid path the thin rectangle, so the friction between the medical fluid and the inner face of the zigzag fluid path is too great to efficiently pass the medical fluid. It takes a long time to pass the medical fluid through the cartridge.
An object of the present invention is to provide a cartridge, which is capable of improving both of the heating efficiency and the flowing efficiency.
Another object of the present invention is to provide a fluid heating device having the cartridge.
To achieve the objects, the present invention has following structures.
The cartridge of the present invention, which is capable of being detachably attached to a fluid heating device including a heater for heating a fluid to be transfused, comprises:
a zigzag-shaped fluid path, through which the fluid passes; and
a contact section being capable of contacting the heater, the contact section being made flat,
wherein a sectional shape of the zigzag-shaped fluid path, which is perpendicular to a flowing direction of the fluid, is formed into a polygonal shape.
In the cartridge of the present invention, the sectional shape of the zigzag-shaped fluid path is formed into the polygonal shape, so that the friction between the fluid and an inner face of the zigzag-shaped fluid path can be reduced and the flowing efficiency can be improved. Contact area of the contact section can be broader, so that the heating efficiency can be improved.
In the cartridge, the sectional shape of the zigzag-shaped fluid path may be formed into a regular square. With this structure, said friction in the zigzag-shaped fluid path can be lower than that in the zigzag-shaped fluid path having a rectangular cross section. Namely, the fluid can be efficiently flowed, and the contact area can be broader.
In the cartridge, area of a cross section of the zigzag-shaped fluid path, which is perpendicular to the flowing direction of the fluid, may be partially changed. With this structure, a turbulent flow of the fluid occurs at positions, at which the area of the cross section of the zigzag-shaped fluid path is changed, so that the fluid can be agitated and uniformly heated.
In the cartridge, the zigzag-shaped fluid path may be formed into a zigzag shape by a plurality of partitions, and width of the zigzag-shaped fluid path may be wider than that of the partitions. With this structure, the contact area can be broader without changing size of the cartridge. Further, heat conduction through the partitions can be made lower, so that the heating efficiency can be improved.
In the cartridge, the zigzag-shaped fluid path may be a zigzag-shaped through-hole, whose both ends are respectively opened in both sides of a cartridge body proper, and the both ends of the zigzag-shaped through-hole may be respectively covered with sheet-shaped members, which are capable of contacting the heater.
In the cartridge, the cartridge body proper and the sheet-shaped members may be molded with polycarbonate. With this structure, heat-deformation of the cartridge can be prevented.
In the cartridge, the sheet-shaped members may be transparent. With this structure, the fluid heated in the cartridge can be visually observed.
On the other hand, the fluid heating device of the present invention comprises:
a heater for heating a fluid to be transfused; and
a detachable cartridge of the present invention.
In the fluid heating device of the present invention, the friction between the fluid and an inner face of the zigzag-shaped fluid path can be reduced and the flowing efficiency can be improved. Contact area of the contact section can be broader, so that the heating efficiency can be improved.